For Sale: HP-71B MultiMod ROM Emulator

[mfleming]

Hi everyone,

The MultiMod ROM Emulator board and optional 3D printed enclosure is now available to those interested in a means of hosting ROMs for your HP-71B. Attached you'll find an order form to fill out and send in for each board you would like. Although you need one form per board, multiple orders will be consolidated into a single shipment. You'll receive confirmation of the order submitted within 24 hours, along with an outline of what will follow. Fill out, save, and send a completed PDF order form to

hp71multimod@gmail.com

The board itself is $65 with free USPS Express Shipping for those in the States. An enclosure can also be included with the order for an additional $20. Shipping outside the U.S. is by USPS First Class Package for an additional $6. I highly recommend the enclosure! Contact Dan directly (twoweims) if you want to separately order an enclosure in a different color or lettering scheme.

There is an additional attachment for a programming sheet for the MultiMod based on an idea from Dan Simpson. The programming pad makes it easier to lay out the ROMs and list the serial monitor commands needed to set up your MultiMod. A couple of examples are given to get you started. Have a look to see what is involved in building your own ROM set.

You can find ROM data files, support scripts, manuals, etc. in the following github repository

https://github.com/mafleming/HP71MultiMod

There are a few things that need to be added or updated in the repository, but you'll find everything there you need now to get started. Source code will follow as the ragged edges get hammered out (formatting & comments, not code!). Eventually schematics and Gerbers will follow.

I'm having quite a time with my newly available ROMs and I hope you will too!
~Mark


Many of you may already have the necessary USB to TTL serial interface cable but here are a few suggestions for those who don't. First up, the ubiquitous 4-wire cable with 5V Vcc, Ground, and 3.3V transmit/receive signals. This will work perfectly well for the task.
https://www.amazon.com/JBtek-WINDOWS-Sup...255&sr=8-2

More versatile serial interfaces can be found in some of the posts below. Either of the DSD Tech adapters can be used for other purposes if you dabble in Arduino programming. I would recommend any of those using an FTDI chip.
https://www.amazon.com/s?k=dsd+tech+usb+...2_ts-doa-p


Edit: Updated Order Form font
2nd edit: For those having problems with the LibreOffice Liberation Sans font, all appears fine on my end. I've replaced the font with Times New Roman and updated the form.
3rd Edit: Liberation Sans font finally stamped out!
4th Edit: Add USB serial suggestions.
5th Edit: Updated MultiMod-ProgrammingPad document. Always check github repository for latest version at
https://github.com/mafleming/HP71MultiMod

[rprosperi]

Suggestion:

Please post a link (e.g. Amazon, eBay, etc.) for a USB cable that is the proper type, not needing special 'anything', just connect and go.

Folks that like to dabble with such things will ignore it and likely comment how 'obvious' this should be. I'll live with the comments, and in fact, I'm already over them.

Thanks Mark.

[Sylvain Cote]

Hello Mark,
Congratulation! Great Work!
An order for three modules has been sent by email.
Sylvain

[ThomasF]

Hi Mark!

Great news!

I have problems saving the PDF after filling it out. I get an error message regarding a missing font, and the email-field is replaced by "morse code".

   

I will send you the form, I hope you will be able to sort it out (will be the same email as I send the pdf from).

Best regards,
Thomas

[Didier Lachieze]

(03-10-2021 12:51 PM)ThomasF Wrote:  I have problems saving the PDF after filling it out. I get an error message regarding a missing font, and the email-field is replaced by "morse code".

I have the same issue when viewing the form with Acrobat Reader, but I've filled the form in Firefox and with Firefox the pdf file looks OK including the contact address. I checked also the file in Google drive before sending it to Mark and the preview is fine.

[mfleming]

(03-10-2021 01:48 AM)rprosperi Wrote:  Suggestion:

Please post a link (e.g. Amazon, eBay, etc.) for a USB cable that is the proper type, not needing special 'anything', just connect and go.

Folks that like to dabble with such things will ignore it and likely comment how 'obvious' this should be. I'll live with the comments, and in fact, I'm already over them.

Thanks Mark.

Hi Bob,

Those little cables are so ubiquitous (in electronics anyway) that it's like asking for a recommendation for a good screwdriver. I'll give you my own criteria for picking a cable and the one I currently use.

First, go for one with an FTDI chip. There are other perfectly good companies that make their own USB to serial chips, but FTDI has a broad portfolio and experience in the field. If imitation is the sincerest form of flattery, then FTDI is also the supplier with the most number of knockoff chips.

Get a cable or interface with all the signals, and make sure those signals are labeled! Those four-wire cables only provide transmit and receive, but if you use Arduino boards or other electronics, you're likely to need some of the hardware handshake signals. The Mench board for instance implements a full hardware serial interface where just Rx/Tx won't do.

Get one that supports multiple voltage levels. There are still applications that need 5V interfaces, but 3.3V is increasingly becoming the norm. It's best to have one board that can be strapped for your target voltage.

A final nice-to-have would be a configuration that lets you use your own USB cable. Nothing worse than being tethered to your PC by a much-too-short cable.

The one I'm currently using is the DSD Tech SH-U09C2 USB to TTL Adapter available from Amazon. You'll need an appropriate USB cable extender with an A Male to A Female connectors of whatever length you choose. There's a plastic case to prevent gefingerpoken und mittengrabben damage, and it can be removed to access less commonly used serial signals. It can also be strapped for 5V, 3.3V, and 1.8V operation. The FTDI chip itself can be configured for things like complemented signal levels as needed by the Sharp PC-G850VS. Well worth the twelve bucks (plus cable).

One last suggestion; don't buy anything under $10, you'll just end up throwing it away.
~Mark

[rprosperi]

Thanks Mark. I have some I can use, I was really just suggesting to add a link to a cable which folks can purchase, which is known to be compatible, and without needing to think about the above.

For example:

Get This Adapter!

[Sylvain Cote]

The DSD Tech SH-U09C5 have control lines header installed and also support 2.5v.

[cdmackay]

hi Mark,

(03-09-2021 11:53 PM)mfleming Wrote:  Edit: Updated Order Form font
2nd edit: For those having problems with the LibreOffice Liberation Sans font, all appears fine on my end. I've replaced the font with Times New Roman and updated the form.

did you actually upload the new version? I've just downloaded it, and I see the same problem…

edit i.e. Adobe reader still complains about Liberation Sans font

I've ordered one anyway, thanks!

thanks!

[mfleming]

(03-10-2021 08:42 PM)Sylvain Cote Wrote:  The DSD Tech SH-U09C5 have control lines header installed and also support 2.5v.

And it appears to support alternate outputs for the RTS/CTS pins. Looks like it's time to update my 2 year old adapter!

[mfleming]

J-F informs that his Math2B ROM has a minor bug fix taking it from rev. 6 to rev. 7. I've updated my git repository with the appropriate math2b7.dat file. All further MultiMods from today forward will have this version of the ROM. So, here's a challenge for those awaiting their MultiMod - on arrival, update the Ultimate ROM collection with the new Math2B image. Here are the steps

- Use POKE "2C000","0" to unplug the ROMs and then turn off the 71.
- Flip over and connect your USB serial cable, ground to board ground, transmit to board receive, receive to board transmit. Configure 19200 baud, 8N1, Xon/Xoff flow control (critically important!)
- Tap (Return) to enter the serial monitor
- Type ? for a list of commands, then "r" (Return) to see the ROM Configuration Table

This will show as

Code:


ROM LIST
ROM 1 16K 1 EOM
ROM 2 32K 2 EOM
ROM 3 32K 4 EOM
ROM 4 16K 0 EOM LAST
ROM 5 16K 5 EOM
ROM 6 16K 6 CHIP HARD
ROM 7 16K 7 CHIP HARD

The first table slot is the 16K Forth ROM in "chip" 1, and the second table entry is the 32K Math ROM starting in "chip" 2 and continuing to "chip" 3. To replace the old ROM image with the new one, download the math2b7.dat file from github, then use the following commands (case not important)

Code:


E 2 (ERASE 2)
E 3 (ERASE 3)
I 2 (IMAGE 2)

Use Send File to transfer the ROM data image to the MultiMod, then tap (Return) a couple of times. Finally, type 'Q' to quit the serial monitor and return control to the ROM emulator. Failure to forget the Quit command will leave the board in serial monitor mode!

Now just turn the 71 on, type POKE "2C000","3", turn the 71 off, then on and use the VER$ command to verify all ROMs are plugged back in.

That's it, all done!
~Mark

[twoweims]

Thank you Mark for your hard work on this.

I have my MultiMod up and running in a very happy HP-71.
Configuring and Programming this is very straightforward.

[Dave Britten]

Got my MultiMod today, and it seems to be working well, according to VER$.

I ran into an issue flashing a ROM image, and the terminal output went haywire, frozen on a "Commit?" prompt a couple seconds into uploading. I had to remove the power jumper to get the module responding again. But now the ROM table is corrupt - it's showing HARD on ROMs 1-5, which shouldn't be possible, and I can't figure out how to unset this. Is there some way to clear/reset the ROM table so I can start fresh? The MCLR jumper didn't appear to do it.

[Sylvain Cote]

(03-20-2021 01:45 AM)twoweims Wrote:  I have my MultiMod up and running in a very happy HP-71.

(03-20-2021 04:35 PM)Dave Britten Wrote:  Got my MultiMod today, and it seems to be working well, according to VER$.

Lucky guys ... mines are stuck at the Canadian customs in BC, I expect to receive them somewhere between the end of next week or the week after.

[Dave Britten]

Hooray, Mark got my corrupt ROM table issue sorted out! Now I've got the latest Math and JPC ROMs flashed to the first 4 pages. Gotta figure out what to do with the remaining 3 pages. I might toss in the Finance ROM, and start putting together a 16-32 KB image with my own selection of LEX files.

[mfleming]

There are a few vulnerabilities in the serial monitor code, none of which I thought would result in an unrecoverable change. Wrong! There is one case (not using Xon/Xoff) in which the default ROM Configuration Table stored in flash could become corrupted. This default is written to RAM each time the processor is reset, and can't be fixed with regular monitor commands.

Luckily I have an undocumented way (other than the boot loader) to update flash via the serial monitor. This was meant to be a platform independent means of updating the ROM emulator code without using the Windows-based boot loader client. I've used this update method to patch a corrupted ROM Table back to its initial default configuration.

I'm updating the documentation to reflect this problem and how to recover. The repair file is available in the DAT directory in the github repository. The recovery procedure will be used to update the ROM emulator software itself when new revisions are available.

I'm sure both Diego and Hans have their stories of teething pains with first releases. I'm *pretty* sure there's no other way to break things, but we'll see. Meantime, save your serial port settings in TeraTerm or other terminal emulator so you start out clean.

~Mark

[twoweims]

Everything is still working great here.
Here is what I have come up with while playing around today:

Code:

HP-71B With MultiMod

>ver$
HP71:2CDCC KBD:C JPC:F05 HPIL:1B RCPY:E HELP:C DIS:B SFTH:F C71:1A MATH:2B EDT:A ULIB:c
>
>show port
0.05  16384  2    ! HP-IL Module
3     32768  1    ! CMT 32K RAM Module          (IRAM)
4     32768  2    ! CMT 32K EPROM               JPC ROM & other misc.
5     65536  2    ! MultiMod Chips 1,2,3,4      C71 & Soft FORTH
5.01  32768  2    ! MultiMod Chips 5,6          J-F MATH2B7 ROM
5.02  16384  2    ! MultiMod Chip  7            Text Editor ROM
5.03  16384  2    ! MultiMod Chip  0            ULIB52
0      4096  0
0.01   4096  0
0.02   4096  0
0.03   4096  0
1      4096  0    ! HP 4K RAM Module
2      4096  0    ! HP 4K RAM Module

[mfleming]

(03-20-2021 04:52 PM)Sylvain Cote Wrote:  

(03-20-2021 04:35 PM)Dave Britten Wrote:  Got my MultiMod today, and it seems to be working well, according to VER$.

Lucky guys ... mines are stuck at the Canadian customs in BC, I expect to receive them somewhere between the end of next week or the week after.

USPS usually takes 4 or 5 days for a 1st Class package to cross the Continent, usually by slow freight train. . .

Good luck!

[Nigel (UK)]

Received it quickly here in the UK. It works! To achieve this I first had to clean the HP-71B terminals with a glass fibre pen - nothing had been connected to them for years (decades?) and although they didn't look too bad, they didn't connect reliably until they were cleaned.

For now, I am (at last!) enjoying the Math ROM. I have not yet attempted to upload the bug-free version, but that doesn't look too hard.

An excellent device!

Nigel (UK)

[mfleming]

The pin sockets can be a bit tight on first use. I press a 1mm pin through each socket and then insert each assembly in an HP-71B for programming and testing. You'll know the board is fully seated in your 71 when there is minimal movement of the top of the case. If it rattles, check the seating!

Enjoy your own ROM setup,
~Mark